The Rule of 72: A simple rule that will change the way you think about money. It's a lesson we should introduce to our children early in life.

The Rule of 72 helps estimate how long it takes for your money to double based on a fixed annual return.

How does it work?

To find the years required to double your money:

72 ÷ Annual Return (%) = Years to Double

Example: If your annual return is 10%, then:
72 ÷ 10 = 7.2 years
£1,000 invested at 10% will double in about seven years.

It also works in reverse: to find the required annual return to double your money in a set time.

72 ÷ Years to Double = Required annual return.

For example, to double your money in six years:
72 ÷ 6 = 12%

Understanding the Rule of 72 can help you see the power of compound interest—a concept that’s not always intuitive.

Start early: Small, consistent investments over a long time lead to extraordinary gains. The secret? Never interrupt compounding.

Don’t wait too long to invest:
Starting later in life means you’ll need higher annual returns to achieve the same results. Quick wealth is often fragile wealth. But remember: it’s never too late to start investing.

While the Rule of 72 can motivate you to save and invest, balance is key.

Live Your Life:
Don’t forget to live your life. What’s the point of working hard and earning money if you don’t enjoy it?

But

Spend Wisely: Avoid spending to impress others. Ask

1. Would I still want this if no one else saw it?
2. Would I still enjoy this vacation if no one knew about it?

A life well lived has minimal regrets.

That is it for today, take it easy until next time.

Read all my “Notes to Self” at view all blogs.

Previous
Previous

Five simple laws about money. You don't want to learn the hard way.

Next
Next

“I have nothing to add”. I was tempted to end the post with the quote and a photo.  But Munger has inspired me and shaped my thinking over the years, I have something to add...